Paper container



. y 7, 9 6. v v w. H. SHAW ET AL 20 6975 v I PAPER CORTAINER Filed May 9, 1954 INVENTORS Wallzam H.5l'zaw John J Moriarzfy ATTORNEY.

Patented July 7, 1936.

p I UNITED STATES PATENT OFFICE PAPER CONTAINER Applicagin May 9, 1934, Serial No. 724,724

Oanad 8 Claim.

This invention relates to paper containers and more particularly to containers consisting of paper, coated with a composition comprising uncured rubber.

In the production of envelopes or containers of moistureproof materials, it is known to employ vulcanized rubber coated or impregnated fabrics, to portions of which is applied a composition of uncured rubber which serves to seal the container when closed.

The object of the present invention comprises a process forvthe production of paper completely coated with a composition containing uncured rubber and the production from such rubbercoated paper of containers which are substantially moistureproof, air-tight and self-sealing.

These objects are attained by applying to any convenient type and weight of paper, by means of a calendering operation, a coating of a composition comprising uncured rubber and thereafter applying a material which renders nonadhesive the exposed surface of the applied coating. The coated material thus produced can be rolled and stored without the various folds adhering to one another, but when the surfaces in contact are subjected to sumcient pressure to fracture the filmof non-adhesive material overlying the rubber coating, satisfactory adhesion between the surfaces results.

The invention is not restricted to the use of any particular type of paper as this will be controlled by cost and the purpose which the product is intended to serve. Thus the paper may be heavy or light in weight, it may be creped or not creped and it may be glazed or unglazed on one or both sides. The only necessity is that it shall possess sufllcient tensile strength to permit of processing. Paper known as latex absorbent in disclosed and Figure 2 is a cross-section of the material, which is enlarged for the sake of clarity and is not drawn to scale. In Figure 1 the material is sealed at the edges, indicated as 2, by pressure and 3 represents the line where the fabric is joined. A zone shown at l is suitable for running the finger over to form a temporary seal which is broken when the container is opened.

The following is an example of the manner in a December 19, 1933 which the invention may be carried out. It must, however, be considered-as illustrative rather than limitative.

Twenty-flve-pound crepe kraft paper of fairly good grade, almost white in color, glazed on one 5 side and unglazed on the other, is fed to a calender of the three-roll or four-roll type where to the unglazed surface is applied a composition consisting of:

This compound is prepared on a rubber mill in the manner well known to the art and is fed to the calender in a warm and plastic condition in accordance with the usual procedure.

To the rubber compound above is added, if desired, a material to impart a slight odor to the compound, as for example, tobacco essence in the case where the finished coated material is to be used for tobacco containers. This tobacco essence is added in the quantity of approximately one ounce to 100 pounds of compound. Essences of other odors or flavors may be added where the material is to be used for a different purpose. The choice of the addition of such an essence will readily occur to those skilled in the art or may be omitted entirely if desired.

About 6 ounces per square yard of rubber compound is calendered to the surface of the paper which, on leaving the rolls, is led immediately to a starching and brushing operation. It isipreferred, in order to prevent the formation of creases, to eliminate all rollers and tension bars between the calender and the starching box, and between the starching box and wind-up.

The starching operation is conducted in the usual type of starching box containing corn starch, after which the material is brushed to remove excess starch and the coated and starched paper is then immediately wound onto a roll, the starch coating serving to prevent adhesion between the face and the back of the paper during rolling or during storage of the finished material.

It is preferred to employ paper unglazed on the side to which the compound is to be applied as this tends to aid adhesion of the rubber film. On the other hand, it is advantageous that the other surface of the paper be glazed if it is desired subsequently to print on this surface,

since the glazed surface absorbs less printing ink. Creping of the paper before processing not only aids adhesion of the rubber compound but improves the feel of the product which is then very soft and pliable in texture. 4

In place of the above mentioned paper, 40 pound white kraft bleached designated M. G. (machine glazed)- has been employed. It is glossed or finished on one side, is pliable in texture and has suflicient tensile strength to permit of processing. Other rubber compounds mayalso be used. For instance, the following has been found to produce satisfactory results:

Pale crepe lbs 19 Barytes bs" 21 Agerite white ozs 2 The amount of compound applied per square yard of area is of course not restricted to that shown in the example since any convenient quantity may be applied by suitable adjustment of the calender.

Similarly, instead of corn starch any other material suitable for rendering the rubber film nonadhesive may be employed. For instance, soapstone may be used but corn starch is preferred.

Rubber-coated paper manufactured according to this process is useful for many purposes. For example, if it is desired to prepare a container therefrom all that is necessary is to shape the material into the desired form and apply suflicient pressure, as by crimping, to the regions where adhesion is required, to fracture the starch covering. A complete and satisfactory seal is thus obtained. This seal can readily be broken without tearing the paper and the container can be resealed by pressure at, or approximating to, the line of previously adhering surfaces. Thus such a. container can be opened and closed numerous times still preserving the package in a substantially moistureproof and air-tight condition. I

This invention further contemplates the production, of containers by crimping rubber-coated paper of the type described in the desired form and thereafter submitting to a vulcanizing treatment thus permanently securing the adhering portions of adjacent films.

Other purposes for which this coated paper may be used include linings for boxes or sacks which are to contain material which it is desired to preserve in a substantially air-tight or moistureproof condition.

It is apparent that many widely different embodiments of this invention may be made without departing from the spirit and scope thereof and,

' therefore, it is not intended to be limited except as indicated in the appended claims.

We claim:

gonna" a composition having the approximate formula:

Pale crepe l s 38 Whiting bs 20 Barytes bs 42 Zinc oxide lbs 5 Montan wax lbs 2 Btearic acid. ozs 6 .Rubber oilbs" 2 and having a coat of starch just sufficient to render the composition tackless but yet adhesive under moderate pressure.

3. An article of manufacture which comprises a flexible fibrous cellulosic base material, a coating comprising tacky sticky unvulcanized rubber compound containing inert pigments. adherently disposed on the base material, and an exposed layer of non-tacky pulverulent material over the coating suflicient to render the coating nonsticky but insufficient to prevent coherence of two portions of the coating when the portions are disposed face to face and a moderate pressure is applied to the base material along a line in a predetermined limited zone.

4. The article in accordance with claim 3 in which the base material is a crepe paper.

5. The article in accordance with claim 3 in which the pulverulent material is starch.

6. An article of manufacture which comprises a flexible fibrous base material, a coating comprising a sticky unvulcanized rubber composition containing inert pigment on the base material, and a coating of pulverulent material on the layer of unvulcanized rubber composition, said coating of pulverulent material being suflicient to diminish the adhesiveness of said rubber-containing coat to the extent that two of said coatings can be placed face to face without cohering when a moderate pressure is applied over a considerable area and to the extent that two of said coatings can be. separated repeatedly without rupturing the rubber containing layer after they have been cohered, but said coating of pulverulent material being insuflicient to prevent the cohesion of two of said coatings when they are placed face to face and moderate pressure is applied along a line in a predetermined zone.

WILLIAM H. SHAW. JOHN J. MORIAR'I'Y. 

